Nowadays, the technique of controlling flow rate by changing guide vane angle had been applied in many fields. Taking the application in air conditioning system for example, the inlet guide vanes that are disposed in front of the impeller inlet of a centrifugal compressor are controlled at different state for varying the flow rate of the centrifugal compressor to adjust the cooling capacity accordingly. Consequently, if an air condition system is failing to precisely control its inlet guide vanes that are disposed in front of the impeller inlet of its centrifugal compressor, generally a sever energy waste can be caused as the cooling capacity can not be controlled precisely.
However, a conventional inlet guide vane is generally designed to be driven by a mechanism composed of linkages and gears, or is a gear disc mechanism being driving to rotate by a driver, and thus such conventional inlet guide vane not only can be very complex in structure, but also is difficult to design and manufacture.